


Slipknot

by riotcow



Category: Sherlock (TV)
Genre: Angsty Mycroft, Anthea/Mycroft referenced, Bondage, Bottomy Sherlock so far, Breathplay, Consensual Underage Sex, Dubiously and nonconsensual underage sex also, F/M, Implied/Referenced Underage Sex, M/M, Multi, Mycroft-centric, Not actually Eurus but read the summary, Sherlock/John obliquely referenced, Sibling Incest, Toppy Mycroft, angst is hot, holmescest, m/m/f, slightly crack-y, snuff fantasy, the smut only involves adults
Language: English
Status: Completed
Published: 2014-12-03
Updated: 2014-12-03
Packaged: 2018-02-27 23:23:02
Rating: Explicit
Warnings: Graphic Depictions Of Violence, Rape/Non-Con, Underage
Chapters: 5
Words: 13,458
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/2710439
Author URL: https://archiveofourown.org/users/riotcow/pseuds/riotcow
Summary: <blockquote class="userstuff">
              <p>I wrote this two years ago, but in light of series four, I thought that some folks who are suddenly looking for Holmescest that includes a sister might be interested. My Sherrinford is a radically different take on the concept than Moffat and Gatiss's Eurus, but I still feel a little smug that I got there first. ;)</p><p>This is sick, dark, explicit smut, with a little plot. Does what it says on the tin; please heed the warnings. There are no explicit scenes from when the characters were underage, but their childhood sexplay (some consensual; some clearly not) is frequently referenced.</p>
            </blockquote>





	1. Christmas Dinner at the Holmes'

It was Christmas at the Holmes’. The brothers had been sniping all morning, as usual, and Mrs. Holmes couldn’t have been more delighted than to have little Rosie and new mum Mary to fuss over on top of everything else.

They had all just sat down to dinner around the Holmes’ family table, which was expanded to its maximum capacity for the occasion. Sherlock’s father had carved the ham and thick slices had been distributed to all, and everyone had had at least a few deep draws from their spirits. John was surprised at how like family this felt, sitting at the table with the likes of Sherlock and Mycroft Holmes and their parents, but also John’s own wife and newborn daughter. It actually felt like _Christmas_.

John glanced around with long-retained soldier’s instincts, playing a whimsical game of guessing how inebriated each guest was. Mary would certainly win any coordination games, as the only person who was stone cold sober due to nursing Rosie, and (as it happened) also a CIA-trained assassin. Both Mr. Holmes and Mycroft were somewhat deeper in their cups than usual, and Sherlock and his mother had probably each had a glass of wine. John himself had a fairly decent buzz going, and felt he deserved it after all the recent nights of changing nappies and warming pumped breastmilk.

This wasn’t the first time that John had marveled at the fact that his life had led him to be the kind of man who sat at Christmas dinner with the most famous detective in the world, along with his brother who secretly controlled the British government. Both of whom were slightly flushed with wine, and with chagrin at their mum telling stories of a time when they were simply two snotty, impossible boys.

John relished these moments. And he relished knowing that Rosie would remember her first Christmases with these people, this family. With Mary here, welcomed, loved. And Rosie, welcomed, loved. He relished them in part because of all he had endured at Sherlock’s hands: two years of stricken grief after the Fall, the rollercoaster of his resurrection.

John tucked into ham and potatoes while laughing at a story that Mrs. Holmes was telling, one which was embarrassing to both of her scowling sons, when the knock came at the door.

Mrs. Holmes stood first, looking surprised. “Who would come by at this hour?” she mused aloud, but she didn’t sound irritated, merely curious.

John turned to Mary, who was passing him a squirming bundle. Rosie was fussy right now, refusing to cooperate with their plan that she doze in her swing while the grown-ups had a leisurely holiday meal. He didn’t mind though, and Mary was exhausted. He pulled Rosie's swaddle a little tighter and started to bounce her against his shoulder, determined to lull her into a nap so that Mary could enjoy her Christmas dinner without interruption.

John had just gotten Rosie somewhat settled on his shoulder when, unexpectedly, Sherlock’s mother gave a loud, long wail.

John and Sherlock locked eyes first, both of them starting to rise, but Sherlock’s eyes flew to his older brother’s only a beat later. Even Mycroft and John -- who also had survived some rough times together --  exchanged glances as the three men got to their feet to go see what had shocked Mrs. Holmes so thoroughly.

Somehow John had forgotten about the swaddled, squirming bundle on his shoulder. “Sit _down_ ,” Sherlock snapped in obvious irritation, sure that John should not bring Rosie in response to a potential _situation_.

He had a point. Mary’s hand on his elbow steadied him. John sat back and split his attention evenly between soothing the baby and listening to the events unfolding in the foyer.

Everyone still in the dining room had gone quite silent as they waited, and the only sound coming from the foyer now was that of Mrs. Holmes weeping softly, though she sounded neither injured nor frightened. Mr. Holmes was now rising to see what was distressing his wife, though both Sherlock and Mycroft had made it into the foyer before him.

And then everyone froze in shock. 

John wasn’t sure what to do, and Mary was obviously waiting on his cue. Both Sherlock and Mycroft had stalled in the doorway, where they had first come into line of sight of whatever was occurring at the front door. John couldn’t quite see from his angle. Mr. Holmes then ground to a halt standing between his two sons, one hand on each of their shoulders.

John heard Mrs. Holmes choke out a name: “Sherrinford.” At this, Mycroft suddenly turned back toward the dining room with a look of panic on his face. 

John exchanged a look with his wife. “Sherrinford?” Mary mouthed, and John shrugged with Rosie against his shoulder. He’d heard the name, but had no idea who it was other than a relative. He wasn’t even sure of this Sherrinford’s gender.

But he guessed that he was about to gain further insight, as Mrs. Holmes’ weeping was slowly calming but was also drawing nearer, and the family matriarch herself was coming back into the dining room with her arm clutched around the shoulders of a tall, dark-haired woman. Sherlock, Mycroft and their father all parted before the pair, and Mrs. Holmes was barreling the younger woman into her chair and then sat down beside her, in the place that had formerly been occupied by her eldest son.

It was an unbelievable display of emotion for any of the Holmes, and John was well aware that both Sherlock and his brother were still looking utterly stricken in a way that John could not recall ever having seen before. John took a closer look at Sherrinford, and was instantly struck by her dark curls, wide smile, by her pale eyes… Jesus, she was a female version of Sherlock himself, wasn’t she?

Mrs. Holmes still had her hands around Sherrinford’s shoulders, and the younger woman slowly untwined those hands, pressing repeated kisses onto them as she attempted to disengage herself. “It’s alright, Mummy, I swear I’m not going anywhere. You can let me go. I promise I won’t run away,” and John and Mary shared a shocked glance.

If Mrs. Holmes was “Mummy,” then Sherrinford was Sherlock and Mycroft’s… sister?

 _No_.

There was no way that Sherlock Holmes had a sister and John Watson didn’t know about it. Not after all this time. Not after all they’d been through.

John’s eyes flew to Sherlock, and he noticed Mary doing the same, and he noticed Mary drawing the same conclusion.

Oh my god, yes. Sherlock was genuinely freaked out. 

This was a missing Holmes sibling.


	2. Dinner and Drinks

Sherrinford seemed a little overwhelmed but was smiling widely at her mother’s emotional display, and she reached a hand out toward her father, who came to stand between their chairs with visibly moist eyes, his arms around the two women. 

“You can’t leave; you can’t just show up like this and then leave again, Sherrinford, darling,” Mrs. Holmes was explaining, anxiously, as she attempted to get herself back under control. “I’m not going to be able to relax until you promise me that you’re staying… please don’t make me sit here in fear that you’re going to be gone again in an hour.”

Dear God. John didn’t know the story, but he knew a mother's heartache when he saw one. His hold on Rosie tightened slightly.

“Mummy, I’m back in London. It’s okay. Please relax. I promise that I’m not leaving again.”

Their mother nearly wailed again with relief, but John saw Mycroft and Sherlock exchange looks of sheer, undisguised terror. In all his years by the latter man’s side, he had never seen such an expression on his face.

Sherrinford turned from her mum to her dad, who stood above them. She stood up and let him embrace her, folding her into his long arms, while Mrs. Holmes gazed up at the pair with shining eyes.

John continued to jiggle Rosie against his shoulder, unsure of any other course of action. Both Mycroft and Sherlock seemed utterly rudderless, and the elder looked like he was on the verge of being ill.

But Sherlock’s mother finally seemed to be collecting herself, and she glanced at John and Mary with a look of embarrassment. Sherrinford reached up and patted her father’s lined cheek with her hand affectionately. “You are so handsome, Daddy,” she told him, making him smile widely, and John wondered when she had last laid eyes on her father's face.

Or Sherlock’s. Because she was finally turning away from her parents, and toward the two men who John had thought that he’d known so well. 

“Sherlock,” she said, her voice thick.

He allowed her a careful hug. John couldn’t exactly say that he initiated it, but neither did he evade it, which he was perfectly capable of doing and John had witnessed on countless occasions to date. No, Sherlock made himself available to this hug, as if it were coming from Molly Hooper, or from John himself. Sherlock even wrapped an arm carefully around her shoulders and gave something that was not unlike a long, slow squeeze, and John was sure that he saw Sherlock breathing in her smell.

She stayed there, pressed against him un-self-consciously for a long moment, while their parents simply beamed at them. Mycroft still seemed not to have fully recovered from his initial shock. Rosie, who seemed unaffected by the thick, unexpected stew of tensions and emotions in the room over the Christmas ham, was finally drifting off against John’s shoulder, making small, newborn noises in his ear.

John felt strangely as if he were watching events unfold in slow motion as Sherlock unwrapped his arms from around the shoulder of this tall woman with the broad smile and pale gaze that matched his own. They pulled away from each other slowly, and their expressions were smirks that mirrored one another eerily.

And then, then she finally turned toward Mycroft. 

The eldest sibling was still adrift on the periphery of the room, his jaw slightly lax and his grey eyes glazed with obvious shock. John never would have thought that he’d live to see the day when Mycroft was the last person in the room to adjust to new developments, but evidently today was turning out to be that day.

She looked at him for a moment before advancing, and he looked back at her in obvious fear. John realized that the dining room had gone perfectly silent again, and that everyone, even Sherlock, was holding their breath as eldest brother and lost sister faced each other.

Mycroft swallowed visibly. He looked like he intended to say her name, but couldn’t. As if taking pity, she said his instead: “Mycroft,” and John was aware that everyone in the family took a collective breath at the sound of his name on her lips.

Mycroft’s hand fluttered at his side. “Sherrinford,” he said, and indeed he choked slightly on the word.

She stopped in front of him, looking him over. John couldn’t see the expression on her face, but he could see damn well that she was not going to get a hug out of Mycroft unless she wrenched it out of him.

Or, apparently, demanded it. “Act like a human being, My,” she said, and as soon as the words were out of her mouth Mycroft complied, wrapping both arms around her and pressing his cheek briefly but firmly against her curls. He stepped back again just as quickly though, and John saw her roll her eyes at Sherlock as they all started to turn back toward the table.

“I’ve interrupted you at dinner. And with guests.” She seemed sincere in her polite regret, and John realized that she didn't seem to be quite as cold as her brothers were. Mrs. Holmes laughed as she waved off Sherrinford’s concerns.

“Sherrinford, there is no poor time for you to come to your own door. Of course you’re sitting down to eat with us. And staying here tonight.” Mrs. Holmes glanced for a fraction of a second at each of her sons, and suddenly Sherlock and Mycroft were both on their feet, fetching another chair and place setting and helping everyone else rearrange themselves. They were suddenly like a couple of helpful alterboys, and John couldn’t help but be intrigued by the effect this Holmes sister was having on the two sociopaths that John had come to know so well.

In short order they were somehow reseated and Sherrinford had a plate of food in front of her, which she proceeded to ignore, while her mother was too distracted with touching her repeatedly to focus on eating. In fact, no one except Mary was getting much food down, and Mary was the practical sort who would get calories on board while she watched the drama play out.

“I’m not sleeping here, Mummy. I’ve got a room in town. But I’ll come back tomorrow for brunch, all right? I don’t want you to spend every moment thinking I’m going to disappear on you. I promise I’m staying, but I like to have my own space. So relax, all right?”

Sherlock was doing his Sherlock thing, slouching back in his chair and watching things unfold while he soaked in all the data he could. John couldn’t eat much with Rosie finally asleep in the crook of his arm. The baby made a noise, and everyone seemed to remember the guests. Sherrinford -- Lord, it was amazing how much a woman could look like Sherlock -- blushed lightly.

“I’m so sorry. You’re Dr. John Watson; I'm very pleased to meet you. And of course this is your wife Mary, and your new daughter. You're all quite famous. I’m so sorry to barge in on your holiday. I’m Sherrinford, Sherlock’s sister.”

John found that it was not hard to come up with a genuine smile for her. “I couldn’t possibly object, with the joy you’ve clearly brought your mother. I’m a new da, myself,” he said with a head tilt toward the bundle on his shoulder, and she nodded.

“I really should be thanking you, John. My brother’s life has been splashed across the front page of every major newspaper in the country for the last few years, but your blog has provided a much more personal window into his life than the ridiculous games that he gets up to with the press.” Sherlock snorted, and she threw him a black look. “Mummy didn’t get to me before it hit the press, and I actually thought you were dead for twelve hours, you shit,” she added.

Mrs. Holmes exclaimed over language at the same moment that Sherlock cut his eyes guiltily toward John, who had endured much longer than twelve hours before being disabused of Sherlock’s death. John found that he couldn’t particularly begrudge it in this case though; he may have wrestled with two years of grief, but it had clearly been a lot longer than that since this woman had last laid eyes on anyone in her own family. John wondered if he was ever going to find out why that was. 

“Don’t take anything from John’s blog at face value. His prose is hopelessly purple,” Sherlock grumbled. John chafed at the insult, but Sherrinford seemed amused. 

“I’m sure it’s more than I would get out of you if I were to try to get you to tell me anything about yourself,” she pointed out.

Sherlock raised one eyebrow, and John thought he saw a flash of hurt in those eyes. “How would you know?” he asked archly, which was as good as Sherlock outright complaining that you-never-call, you-never-write.

Sherrinford looked taken aback, but only briefly. “And how proceed the plans for world domination, Mycroft?” she asked across the table. “I put you at about two years ahead of schedule, yes?”

“Three, actually.” Mycroft’s voice was slightly faint, but otherwise composed. “Anthea has handed me some unplanned for advantages.” He sounded entirely serious.

In this fashion she cycled her attention through the various members of her family, but it didn’t take long for John to realize that she never allowed the inquiries to be turned around back on her. Mary made an attempt or two, and Mrs. Holmes made one, all of which were redirected back to a topic concerning someone else. She seemed genuinely interested in all of their lives, even John and Mary’s, but was extremely unforthcoming about her own.

But she was a pleasant conversationalist and had a fair feminine measure of the Holmes charm, an interest in dandling Rosie when she got a turn, and an ability to reduce either of her brothers to silent apprehension with no more than a glance. John appreciated all three. It was strange... she was so similar to Sherlock in particular, that having her suddenly drop into the middle of Christmas didn’t feel quite as much like a new addition as it should have.

It was still a hell of a mystery, though, and John could tell that it was driving Mary nuts that the whole family was just acting as if the reappearance of a missing sibling didn’t warrant any further explanation. Mycroft, who had started dinner a little tipsier than John could remember ever previously having seen him, had gone through a long period of being terrified sober after his sister’s arrival, and was now was working his way through a series of tumblers full of an expensive scotch. 

Mr. and Mrs. Holmes wound up retiring on the early side, as it was clear that Mrs. Holmes was exhausted after the shock of her evening. She had teared up again upon bidding her daughter goodnight, admonishing her to keep her promise to return for brunch, and that really she just ought to stay the night like her brothers and the Watsons. Mary took Rosie to the guest room to put her down -- it was as John was bidding them good night that he realized that the “guest room” must be the room that had belonged to the daughter of the family once upon a time. 

John stayed up for one more round with the siblings after their parents had retired. Mycroft sat furthest from the fire in a wingback chair, still looking pale and peaked several hours after Sherrinford’s arrival, and John could have sworn that his hand was trembling intermittently. Sherlock had seemed restless since everyone abandoned the pretense of dinner, and Sherrinford poured herself a glass of wine and seated herself on the arm of the couch, regarding her brothers shrewdly now that their parents had departed.

“So, John,” she said abruptly, in a bright voice. “You probably know both of my brothers better than any other single person.”

John locked eyes with Sherlock. He looked… resigned. Sherlock barely nodded, but it was enough. Sherlock was giving John permission to be pulled into whatever he was willing to be pulled into. Whatever the family secret was, Sherlock didn’t feel the need to protect it from John.

“Yes, probably. Mycroft's PA would know him much better than I do, but she doesn’t know Sherlock as well as I do Mycroft, so I suppose that makes me your man.”

Sherrinford grinned and went to the sideboard, where she picked up the bottle that John had been drinking from and brought it to him, refilling his glass showily. John was tempted to laugh, but he wasn’t really out to see Sherlock discomfited. He was just so damned curious, and Mycroft looked like he was about to have an aneurism.

“Then I can’t resist asking for your opinion on a very important matter, one which I’ve spent the last twenty-five years considering. Would you mind terribly much?” She was back on the arm of the couch, her feet tucked up under her thighs like a cat.

Sherlock’s brow furrowed, clearly irritated at the theatrics, though John had to think that it sort of served him right. She hadn’t even staged a suicide, not to John's knowledge.

“I’ll help if I can,” John said, and he meant it. He didn’t know the back story here, but if Sherlock’s sister was going to be a part of his life again, John would do whatever he could to smooth the way.

Sherrinford arched a brow at John. “Tell me, Dr. Watson: these brothers of mine... are they _good_ men, do you think?” At her words, Mycroft let out a small, strangled sound of dismay and closed his eyes, reaching up with one shaking hand and pinching the bridge of his nose. His sister ignored him.

John didn’t hesitate, as taken aback as he was by Mycroft’s reaction. “Yes. Of course they are,” he said immediately, firmly.

She didn’t respond for a moment, just studied John’s face like she was deciding whether she believed him or not. It was like Sherlock’s own eyes in a woman’s face. He had no question now of whether she shared her siblings’ gift.

Sherrinford took a sip of her wine. “Both of them?” Now she glanced at Mycroft, who had mostly managed to collect himself again and was staring stonily at a spot on the floor.

John followed her gaze, and found himself feeling surprisingly bad for Mycroft. He didn’t know why he was so terrified of his sister -- Mycroft Holmes, who had been nicknamed The Iceman by the most evil man that John had ever personally met. But it was clear that Mycroft was having one of the worst nights of his life, and that everyone around him knew it.

John looked back to Sherrinford. “Yes, both of them. Even Mycroft. He’s dangerously cold, it’s true. And yet he’s chosen to devote his intellect, this _gift_ that you three have, to protecting the Commonwealth. That makes him a good man, in my book.”

Mycroft finally looked up then, at John’s words, a brief expression of surprise, and then, perhaps, even a fleeting look of gratitude on his haggard features. Sherlock just looked calculating as he listened to the exchange between his sister and his partner.

She glanced at Sherlock then. John squinted at her, trying to guess if she was older or younger than Sherlock. The age difference with Mycroft was apparent, but John couldn’t quite order the two younger Holmes.

“I caught that look at the dinner table,” Sherrinford told John, the edge still present in her voice. “Sherlock let _you_ go a lot longer than twelve hours before you knew that he wasn’t dead.”

John couldn’t hide the shadow of pain that he knew crossed his features. “Two years.”

He didn’t think that he sounded angry. He hoped that he was right. From her smile, he didn’t think that he was. She had a certain predatory edge in common with her brothers, and for the first time John wondered if a more feminine Holmes really was much softer than her brothers. Maybe not.

“Was it difficult to forgive him?” Her eyes were taking him apart, and John found himself bristling slightly.

“Yes, it was extremely difficult,” he admitted, tapping his fingers on the arm of his chair. “But I did, because this man’s friendship is worth that much to me.”

This time, she was watching Sherlock as John answered. Whatever she saw there, it seemed to finally thaw her, just slightly. Perhaps it was the look of genuine relief on Sherlock’s face. John was aware of how much the events since his return had brought an end to Sherlock’s previous habits of taking John for granted. Sherlock had become positively vocal about his affection, relatively speaking, especially with the addition of Mary and now Rosie to their lives.

“And how does it work between the two of them, then, between Mary and Sherlock?” Sherrinford asked John bluntly. “Do they trade you back and forth per night of the week?”

John looked confused and Mycroft actually made a low, amused sound. “No, I sleep with my wife every night, just like other men,” John clarified. “Sherrinford, Sherlock and I are… I know that ‘friends’ is a weak word for it, but at any rate, it’s not like _that_.” 

She looked surprised, glancing back and forth between the two men. Sherlock was blushing, which was odd, because people had been alluding to the two of them sleeping together since Mrs. Hudson started in the very first day that they moved in together, and Sherlock had never _once_ blushed over it before.

John didn’t know why, but suddenly the tension in the room -- which had already been substantial -- was so thick that it was almost hard to catch a breath. John took an inventory of the siblings, and realized that Sherrinford was now gazing at Sherlock with an expression of pity, then shot Mycroft a truly furious look before smoothing her features.

“I’m sorry, John, I misunderstood. But now that you point it out, of course it’s not like that. Why would it be like that, when Sherlock doesn’t do ‘like that’ with anyone, does he?” Her voice was venomous.

John didn’t quite understand what she was getting at. “Uh… no. I don’t think so, really. It’s, uh, not his area, he says.” He didn’t know why he was speaking for Sherlock, who was capable of speaking for himself.

“I’m perfectly happy the way that I am,” Sherlock snapped, and again, John had never heard him be defensive about it before. He blinked.

John’s eye was suddenly caught by Mycroft upending his tumbler and then immediately refilling it, his tremor having grown quite bad now. What was… John didn’t understand the connection. Was _Mycroft_ somehow responsible for Sherlock’s inability to deal with sex, was that what they were implying? That didn’t make any sense.

Sherrinford stared at Sherlock. “Well, I’m very glad to hear that you are happy this way. I, however, am _not_ ,” she said in a flat voice, crossing her arms and looking back at John. “The reason that sex is not Sherlock’s area, John, is because he can’t stand to be touched. Surely you’ve noticed that?”

Sherlock looked surly, but John just shrugged. “Sure, I’ve noticed. Mycroft is similar, I think, isn’t he, but maybe not quite as bad? I just assumed that it’s, you know, like a side effect. Of the Holmes brain, or something.” Sherlock made a noise of disgust in the back of his throat at John’s theorizing.

She clearly just barely managed to restrain herself from openly rolling her eyes at him. “Yes, sure, you could say it’s a side effect. Of _one_ Holmes brain, anyway,” she sniped toward her eldest brother.

John could tell that Mycroft and Sherlock were avoiding one another’s eyes, and Sherlock was still actually blushing.

“Very well, Sherrinford,” Sherlock said, going on the offensive against his sister instead of enduring the tension in the room in the wake of her accusation. "If you’re going to go for the jugular -- and you certainly have every right to do so -- then let’s all get down to it, shall we? If you’re actually going to see Mum and Dad again, then I’m sure Mycroft and I will both be quite grateful for you to take your turn escorting them to their insipid idea of entertainment.” He was speaking rapidly and holding himself very still. “But what do you want from me? From him? Let’s just hear it, so that Mycroft can finally resolve his panic attack and John can get his curiosity about my disowned sister satisfied.”

She raised her eyebrows at him during this speech, while Mycroft went from white to absolutely green. “Sherlock, _stop it_. Sherrinford is entitled to take as much time as she cares to getting to the point.” He'd barely spoken in hours, and his voice was strained.

“Why?” Sherlock was still in belligerent mode, and it was clear that Mycroft was wishing that he wasn’t. “She’s had twenty-five years to consider our punishment. I for one would simply like to know what it’s going to be.”

John didn’t want to, but felt obliged to clear his throat. “I can step out --”

Sherlock threw him a reproachful look and John subsided again. Sherrinford and Mycroft ignored him.

She was staring at Sherlock. “ _‘Our_ punishment,’ Sherlock?” she echoed.

That took him aback, and he tilted his head at her. “Well,” he said awkwardly, with that wry twist to his mouth. “Yes?”

Sherrinford uncurled, turning her entire body toward the brother that she resembled so closely. “Why should you be punished for Mycroft’s actions?”

It was clear that whatever actions she considered Mycroft to be responsible for, Sherlock had not been thinking of in the same way. He seemed confused by Sherrinford’s disagreement. It left John wondering if he was finally encountering the source of the original falling out between the brothers. 

Sherrinford stood up and approached Sherlock, who had stayed on his feet on the other side of the coffee table for the entire conversation. She was tall, nearly as tall as he, and Mycroft’s eyes were glued to his younger siblings as she approached him. Moving slowly, she reached out and picked up one of his hands from his side. John saw both of them hitch a breath as her fingers touched his palm, and she stared directly into his pale eyes with her own.

“There is no punishment, Sherlock,” she told him gently. “Not for you, and not for me. Not even for Mycroft, unless he needs it. But I think that we have all three punished ourselves enough, don’t you?”

 _Now_ , John was certain that he no longer ought to be in this room anymore, regardless of Sherlock’s repeated cues to the contrary. He actually found himself standing up and backing out of the intense, frightened tension of the room without saying a word. It was impossible to do so without Sherlock or Mycroft noticing, and John was starting to suspect the same of this long-lost sister, but they all allowed him the fiction. That, or he no longer rated as important next to whatever the fuck was happening.

However, he was not as completely unobservant as Sherlock thought he was, though after the fact, John wasn’t exactly sure that he was glad that he had noticed. It was certainly the thing that sent John’s imagination into overdrive, drawing him back into the hall where he listened to the rest of the evening’s events. He noticed it first of Sherlock, which was what sent his eyes to Mycroft just before he backed out of line of sight.

Sherlock, frozen in place with his sister holding his hand. Face a study in conflict. And clearly turned on.

Sherlock had an _erection_.

John had lived with this man for years, had gone through an incredible range of experiences with him, and had never once seen him display even the most fleeting or lackluster of hard-ons. Until this moment, John had believed that Sherlock didn’t _have_ a sexual response cycle.

And then: Mycroft, who looked frankly miserable, his knuckles white on his tumbler, also was gamely trying to ignore his own bodily responses to the events that had just been upgraded to Whatever The Fuck Was Happening.

And John exited, stage left.

He crept down the hall and into the bathroom, where he first took the opportunity to actually relieve himself, as Sherrinford had plied him with a substantial amount of whiskey on top of a long, festive day of drinking. The soothing sensations of taking a piss actually helped him clear his mind just a few percentage points, after which he proceeded to splash some cold water over his face and run his wet fingers through his hair. Then he leaned over and took a long, deep drink from the cold tap, just like in his army days.

 _Think_.

One: Sherlock had a long-lost sister, whom he apparently had not seen in twenty-five years. Since he was thirty-eight, he would have been about thirteen the last time he saw her.

Two: Mycroft was seven years older than Sherlock, so he would have been about twenty. 

Three: Mycroft did something terrible, to Sherrinford, possibly also Sherlock, something that Sherrinford blamed for Sherlock’s asexuality, and… had she implied her own asexuality as well?

Because of something Mycroft had done to her? To them? Had Mycroft _molested_ his younger siblings? Sherlock seemed to blame himself for something, but Sherrinford clearly thought of him as innocent. Or maybe as mostly innocent. 

Was that what they had been implying out there? Seriously?

Bloody Christ, what had these people gotten up to as children?

John wasn’t so sure that he wanted to know any more, but he knew that he _had_ to know. That Whatever The Fuck Was Happening out there was still happening, and it was something with vast implications for Sherlock’s well-being, for his life. 

John needed to know. He didn’t think of himself as the kind of man who eavesdropped, but he had developed some extremely flexible moral thinking in his years as Sherlock’s assistant. He also assuaged his guilt in that it had genuinely seemed like none of the three of them had given a damn about John’s presence as Whatever The Fuck had begun unfolding, and so he was really just saving Sherlock the trouble of needing John to drag it out of him later.


	3. Drinks and More Drinks

“There is no punishment, Sherlock,” Sherrinford explained as gently as she could to her tense, suspicious brother as she carefully reached out for his hand. “Not for you, and not for me. Not even for Mycroft, unless he needs it. But I think that we have all three punished ourselves enough, don’t you?”

Sherrinford was aware of the sound of John Watson slipping silently from the room without so much as a by-your-leave. The army doctor was quite good, on a number of levels; she could see why Sherlock relied on him. He provided an invaluable steadiness to Sherlock’s life -- the two men complimented each other perfectly. And John was apparently straight as a bloody arrow, with wife and child in tow, and yet madly in love with his best friend. 

So Sherlock was utterly asexual, but the sex thing had never become an issue for them, and now it apparently presented no conflict to bring Mary and Rosie into the fold. Sherlock had managed to build an odd, lovely little family for himself in spite of the profound handicap that Mycroft had inflicted on both of his siblings.

She had no idea how she had managed to read Sherlock and John so wrongly… she should have known that Sherlock hadn’t come out of it any less warped than she had. It proved once again that there was no substitute for direct, eyes-on observation. It was a stupid, naive mistake, now that she reviewed previous data in light of this new information.

She should have known. She’d only thought Mycroft had turned Sherlock against the touch of _women_ other than Sherrinford. After all, it was really only the touch of men -- anyone but Sherlock or Mycroft -- that made Sherrinford truly want to throw up, that made her feel like she was going to crawl right the fuck out of her skin in order to escape the sensation. She could usually endure occasional casual touch from most women, and had even managed a handful of actual sexual encounters with the woman that she’d fallen the most deeply in love with, though none of those encounters had turned out in a fashion that could be reasonably called “successful.”

So she’d foolishly assumed that John and Sherlock had that sort of thing going on. But no, it turned out that Sherlock had simply fallen for someone who didn’t require, expect, or desire sex of him. It was a tidy solution, all around, and one that Sherrinford wished that she’d managed for herself.

It didn’t matter. Right now, Sherlock’s hand was finally in her own. She had been twelve years old, the last time that she touched him, the last time that they had breathed the same air, stood on the same ground. And finally, twenty five years later, she was finally touching him. His body. His skin. Her brother. Sherlock.

She slid her fingers across his palm, doing her best to hide her reaction to the flutter of his heartbeat in the thin skin of the heel of his hand. He was staring into her eyes, and it was written across his face for all the world to see that he could not have looked away from her even if he had wanted to. He was hers, he was all hers just like Mycroft was going to be hers, she knew it was true, and right now that was all that mattered.

Sherlock seemed to be struggling for what to say next. It was okay, she could be patient. She could feel Mycroft’s eyes on them, and she was content to make _him_ wait as long as Sherlock needed.

“I -- you should know that I don’t actually deserve John’s forgiveness,” Sherlock finally said, uncomfortably. “That is a mark of his character, not of my decency. John’s infatuation with me, it... distorts his view of me, considerably.”

Sherrinford smirked. “That’s what you say. I suspect he would disagree. I’m not sure he’s got any rose tinting left anymore where you’re concerned, not after the hell you’ve put that man through.” 

She reached out and took Sherlock’s other hand, held both his palms and rotated them outward, letting her eyes fall to the lines of his exposed wrists. She felt a little lurch of desire at their interlaced fingers, touching him again after these long, lonely years, her body starting to stir, to respond, as it would for no one else.

She knew that he was feeling it too. She _noticed_. Sherlock’s body was speaking loud and clear, whether the man seemed conflicted about it or not. He was also staring at their hands, entranced by the stimulus that was causing his body to respond for the first time in multiple decades.

Sherlock’s eyes traveled up her arms and shoulders and throat, back to her mirror-blue eyes, and whatever he saw in hers made him narrow his in return. “What _of_ forgiveness, then, Sherrinford? If you deem that no punishment is necessary, does that mean that the crime is indeed forgiven? I’d like to know, as I have to admit that I’m feeling... skeptical, regarding your intentions tonight.”

Sherrinford sighed, a little hurt, and released Sherlock’s hands, despite the wrenching sense of loss that it caused her to stop touching him. She turned away from him in frustration and found herself regarding the striking figure of her eldest brother, dressed to the nines even for Christmas, and watching them with avid attention. Mycroft was clearly both drunk and on a complete hair trigger, which was a dangerous state to be in for a man with his power and his responsibilities.

In fact, looking at him square on like this, nothing between them but approximately five paces, she realized that he was looking at her with open hunger on his harsh features.

 _Ah_. Maybe she’d been starting with the wrong brother after all. She’d wanted to thaw Sherlock herself, enlist his help in taking Mycroft apart in the way that the eldest and guiltiest was going to need. But maybe Mycroft was ready to be taken apart all on his own. If so, Sherlock was going to be toast in the end. He was no match for them both and he damn well knew it.

Mycroft was watching her eyes. Mycroft was watching her think. She needed to watch out for that; unlike her brothers, she’d forgotten what it was like to be in the room with other people who were capable of doing it.

But she also realized that Mycroft was still wide open, utterly vulnerable. He was watching her eyes in self-defense, because he was entirely at her mercy.

“Well, My. We’ve got to do this, so we might as well get it out of the way.”

Mycroft nodded and spread his hands. “Very well, Sherrinford. You may begin.”

Sherrinford chewed briefly on her lower lip. “Do you regret it?”

“Do you want the correct answer, or the honest one, dear sister?”

She grinned at him, and jerked her chin. “Don’t insult me.”

Mycroft raised an eyebrow and spoke calmly. “I cannot _regret_ the only gratifying sexual experiences of my life. I can and do deeply regret any damage that I did to you, or to Sherlock, in my youthful, reckless pursuit of that gratification.”

Sherrinford digested this answer for a long moment while Mycroft patiently awaited her judgment. He looked calmer now that the confrontation was actually occurring. He smoothed his palms down his trousers to his knees.

After a moment, Sherrinford’s expression relaxed. “Well, then. You basically fucked yourself, too, didn’t you? Almost as badly as Sherlock and I.” 

Mycroft’s mouth twisted in a grimace. “Perhaps. Either that, or we all three actually came pre-fucked, as I once tried to explain to you at some rather unpleasant lengths. I suppose that now we’ll never know for sure.”

Sherrinford crossed her arms and looked Mycroft up and down assessingly. “All right. So. Let’s get to the point, then. What _would_ you let me do to you, Mycroft? In punishment, if I did want it, and frankly, _you’re_ hoping I do.”

Mycroft didn’t seem surprised by the question, nor did he hesitate in answering. “You cannot disrupt my work. You cannot leave marks on my body that would be visible when I’m dressed. You cannot harm Anthea, or Sherlock’s family.” Sherrinford blinked at his immediate response, gratified to realize that he’d must have been thinking hard about this question since the moment that he saw her face.

She shot a grin at Sherlock. “How sweet, Mycroft bargaining to protect _your_ family. You two boys have mended bridges, haven’t you?” She returned her attention to Mycroft. “Tell me, My, do you and Sherlock ever actually _talk_ about the shenanigans that we got up to as kids? Or do you both just pretend that it never happened? What I mean is, is it awkward that Sherlock is a 38-year-old virgin because of you?”

Sherlock interrupted, flushing hotly. “ _No_ , Sherrinford. You work out what you need to with Mycroft about the things he did to you, but don’t campaign on my behalf. I told you, I’m not like you. I don’t care that I don’t want sex, and I never liked touching anyone else even before… _before_.” He sounded annoyed at not knowing how to refer to the events that had transpired between them as children.

Sherrinford grinned and advanced on Sherlock again. He was so surprised that he let her back him up a single step, but when she heard the way his heel hit the ground, she knew that she wasn’t going to get a second one out of him.

“You don’t care?” She was smirking. “I might believe that, dear brother, if you hadn’t been just as hard as Mycroft was the moment that you realized that it was me at that door. You’re both lucky that Mummy was so emotional that she managed to avoid noticing.” Sherrinford didn’t actually press against her brother anywhere, but she let herself get so close to him that he would be able to feel the heat radiating off of her body through her clothes, that his nostrils would be filled with her scent. As if on cue his body responded to her proximity again, and she laughed unkindly in his flushed face.

She heard Mycroft hiss at her brazenness as she relished Sherlock’s look of irritation. She reached out and ran her fingers over the bulge at Sherlock’s groin, careful to keep her touch at exactly the level of firmness that she herself preferred. She followed the length of him, then wrapped her hand around his shaft, cupping him securely through his trousers. Sherlock was poleaxed, suddenly breathing hard. He clearly had no idea how to respond to or even to process what he was feeling, and so he wound up rooted in place beneath her touch.

Sherrinford pressed against the full length of him now, her mouth lifted toward his ear, her fingers continuing to explore him. “I wonder, sometimes, Sherlock, if maybe you’ve just forgotten, or deleted, all the data that we gathered as children. Because I haven’t, and I remember how heart-stoppingly _good_ it all felt, the things that Mycroft made us do. And the things that we did on our own.”

Sherlock’s breath was ragged now, his adam’s apple moving as he swallowed. His right hand twitched at his side but he refused to lift it.

“Hasn’t it been the least bit tempting, allowing him to remain in your life all these years, knowing what he’s capable of doing to you? You know that’s why I couldn’t stay near him, don’t you? Mycroft never would have touched either one of us again after you went to Mummy. It was me who couldn’t be trusted, Sherlock, that’s why I was the one who went away. If I’d stayed, I know that I would have wound up going back to him, _begging_ for it. Didn’t you ever consider it?”

His cock was definitely growing heavier and hotter in her palm as she spoke, even as his features twisted in distaste at what she was saying. “You know that Mycroft is actually heterosexual, Sherrinford. He was primarily interested in me as another way to get to you, and as another subject to experiment on.”

She frowned and relinquished her hold on him, and Sherlock exhaled in obvious relief. She turned on Mycroft again, and he just looked down his nose at her, waiting.

“Sherlock, you know as well as I do that the hottest bloody part of it for him was the _incest_ ,” Sherrinford said.

Then she turned and pointed a finger at her older brother. “But queer or not, _you_ must have been gagging to get your hands on someone who could actually make you hard over all these long, lonely years of toil. You know, I may have misread Sherlock and John, but I’m _certain_ that your assistant’s duties extend to every room of your home.”

Mycroft didn’t look the least abashed about that. “She takes care of me in every way that I will allow, and I sometimes allow her liberties. She has always upheld my confidence.”

Sherrinford tilted her head, a wicked gleam in her eye. “I’ve seen her, you know. She’s astonishing, a breathtaking woman. Can she bring you off?”

Mycroft looked deeply exhausted. “Occasionally.”

Sherrinford was on a roll now. “And Sherlock right there, being such a fucking brat, acting out every chance he could, stressing out Mummy. And you with this _incredible_ tool in your arsenal that you could have deployed at any time, and you know that you would have gotten his attention. You certainly wouldn’t have had to brook nearly so much of his bullshit over the years. Why didn’t you do it, My? You must have wanted to.”

She watched Mycroft lick his lips and look up at Sherlock. She glanced over to see that he now appeared to be trapped by her spell, as he was clearly interested in Mycroft’s answer to her awful questions.

Mycroft nodded at him, and then met her eyes, and for the moment he had himself under control. “Frankly, Sherrinford, I had thoroughly learned my lesson about compromising my ambitions for the future. I resolved that first night as I sat waiting in Mummy’s study that there would never be any more fodder for this particular fire. I couldn’t stop you two from doing whatever you would with each other, but I knew that I would never lay a finger on either of you again.” He gave Sherlock a pointed look as he said the last part, and the younger brother’s brow furrowed.

“Really?” Sherrinford looked skeptical. “And yet, dear brother, I notice that you just gave me blanket permission to do just about anything I want with you.”

Mycroft just shrugged. “You’re initiating this, Sherrinford, but I have no reservations. Why should I? You quite possibly could have destroyed me, but you didn’t even try, and because you restrained yourself, I’ve been able to make good on my ambitions. At this point you certainly deserve whatever it is that you want of me; you’ve played the long game masterfully.” He glanced around. “On the other hand, I’m not sure that the sitting room of our childhood home with our parents asleep down the hall is an ideal venue. For anything, ever.”

She stared at him thoughtfully for a moment, then looked to Sherlock, whose expression could probably best be described as troubled.  “What do you say, Sherlock? Perhaps you don’t _mind_ being broken, but that doesn’t mean that you have to live with it.” 

Sherlock’s eyes were unfocused, in the distance, but he came back to himself quickly at her question and drew himself up to his full height. “I’m not going to let the two of you start plotting together behind my back, if that’s what you’re asking.”

“That’s one way to put it. Fair enough.” She turned back to Mycroft. “Make some time on your calendar. Soon. Make some arrangements that are secure enough for you, and let Sherlock and I know the details.” She spread her arms in a questioning fashion. “All right?”

Mycroft tilted his head in acknowledgment. “As you wish, Sherrinford. Will this weekend do?”

She grinned widely and reached out and took Sherlock’s hand, squeezing it just like she had when they were children. It was a reaction of genuine joy, and she saw both of her brothers pause a moment in the face of her uncalculated expression of sentiment. “Yes, My. That will do just fine.”


	4. A Surprise For Sherlock

“Sherlock.”

Silence.

“Sherlock. I’m talking to you.”

“Go away, My. I’m watching these ants.”

“I know you are. But you’re going to want to be doing what I’m about to propose even more.”

Silence.

“What is it?”

“Sherrinford and I have a surprise for you.”

Silence.

“What’s the surprise?”

“I figured out how to improve the rigging that Buono and Bianchi used.”

“How?”

“I’ll show you. Sherrinford let me try it on her again, the better way.”

Silence. 

“I don’t care. I already figured out how to fix it.”

“Did you try it?”

Silence.

“Sherlock? There’s more to the surprise.”

Silence.

“What?”

“I convinced her to take her clothes off first this time.”


	5. In A Safehouse Somewhere

Mycroft’s phone vibrated in the pocket of his waistcoat, and he quickly rinsed off his hands and dried them on a dishtowel before checking the screen and confirming that, yes, that particular text meant that Sherlock and Sherrinford had arrived, together, just like he’d expected them to. Just like they would have twenty-five years ago, before he tore them apart.

Mycroft removed his apron and hung it in its place, then picked up the first bottle of wine that he’d selected for the evening. He’d given some thought to the question, to which bottle from his cellar would best mark the unusual milestone of disowned-sister-gets-her-comeuppance-after-twenty-five-years. She certainly deserved his finest. 

God, they were beautiful, his younger siblings. Sherlock with those cheekbones and that ridiculous head of curls and Sherrinford, who didn’t hesitate to use that breath-taking smile to her benefit. He was wearing that ridiculous coat of his, which he flung over the back of the nearest chair before pouring his long, lanky frame into its companion wingback. 

Mycroft caught himself frowning at Sherlock’s slouch, then refocused his attention on Sherrinford. She was dressed plainly in dark trousers and a button-down shirt, which only served to emphasize how strikingly alike she and Sherlock still were in appearance. He knew that that was for his benefit specifically, and he found himself appreciating that she bothered. This was clearly the point in the evening when his palms would have started sweating if he hadn’t taken a beta blocker beforehand.

He smiled, and it was a tight smile, but he didn’t see any point in hiding it. “Sherlock, Sherrinford. Welcome. Have a glass of wine; Sherlock, would you like one also?”

They both accepted, and Mycroft found himself pouring wine in the middle of the strained silence which had filled the flat the moment that the two younger Holmes arrived. Her mood was alert, expectant, but she didn’t seem quite as _angry_ as she had at Christmas. Sherlock had a tense, distracted air about him, as usual.

Mycroft didn’t see any point to small talk. “So how does this work, sister dear? We have complete privacy here, for as long as you want. All of our needs can be provided for if you so desire. So what are we doing?”

Sherlock was ignoring them ostentatiously, doing something on his phone with one hand at lightning speed as he sipped his glass of wine. Sherrinford threw him an amused look before she turned her attention back to Mycroft and smiled at him. It was a friendly smile, perhaps slightly challenging, but certainly not hostile. At that moment he could see the little girl she had been, his little sister.

“You’ll be gratified to hear that you did indeed strike a chord on Christmas night,” Sherrinford explained. “You told us that you vowed when you were twenty that you were never going to lay another finger on either Sherlock or I. But that _this_ ,” -- and here she gestured vaguely around them, indicated the luxuriously tasteful but clearly uninhabited flat, probably a safe house for a special class of fugitive -- “is different, because I’m the one initiating it.” Her brow was creased with obvious consternation at this thought.

Mycroft raised his eyebrows. “Yes?”

She spread her hands and regarded him. “Well, upon some reflection, I’ve decided that the best strategy with the man that you’ve turned out to be is to let you answer for your own mistakes. ”

“And how do I do that?” Mycroft asked, his voice carefully neutral. 

“I don’t know, My. How _do_ you do that?”

Sherlock was still texting, almost certainly to John, but Mycroft could tell that his younger brother was attending to their words very closely. That was when Mycroft caught on to what she meant. 

“Ah,” he said, abruptly. 

He stood quite still for a moment as he and Sherrinford regarded each other thoughtfully, then he nodded and paced over to the window. He peered down onto the street below them for a moment, taking a moment to turn everything over in his mind again from this new perspective, his hands tucked into his pockets. Sherrinford seemed content to give him a moment to adjust to the idea, for which he was surprisingly grateful.

After ninety seconds (actually eighty-eight) Mycroft turned back toward his siblings and looked them both over in a starkly assessing fashion. Sherrinford grinned in response to that look, and Sherlock finally put down his phone. “What?”

“Sit down, Sherrinford,” Mycroft ordered, indicating with his eyes that he wanted her in the chair arranged opposite Sherlock’s in front of the fireplace. She obeyed easily, as she always had — she’d never struggled against her own obedience the way that Sherlock had — then gazed up at him expectantly.

“You are both still virgins?” he asked, satisfied that he got the words out in an even voice. 

Sherlock snorted. “Allow me to save you some time, Mycroft. You and Sherrinford together comprise the entirety of my sexual history.” Sherlock had a faint blush on his cheekbones, but seemed otherwise nonchalant about it.

Mycroft nodded, then regarded Sherrinford expectantly. She looked quite uncomfortable, but she didn’t balk. “I had one lover, for a few months. A woman. We had a handful of encounters, none of which turned out all that well... well, for either of us, honestly.”

Mycroft allowed himself to pace to the far side of the sitting room, once, and back. “And you have both been unable to abide the touch of other people ever since Sherrinford left? Sherlock, I’ve seen John touch you. You don’t cringe.”

Sherlock’s mouth twisted wryly. “I can stand contact from John, as well as Mary and Rosie, as it turns out. I do have to concentrate a little, so I can react poorly if I don’t know for sure that it’s one of them touching me.” He looked sulky at providing this information.

Again he turned his attention to Sherrinford, who looked scornful. “Sometimes I can stand casual touch from other women, sometimes I can’t. Men always make me sick.”

Mycroft paused and regarded his seated siblings, both of whom gazed back with identical expressions of vague frustration. And Sherlock had claimed that he didn’t mind? Mycroft almost wanted to laugh at the awful stew of emotions that flooded him at the answers to their questions. Nothing happening in his head right now reflected at all well on his character. “Do you know, my dears? I had no _idea_ that my untutored attempts at training would be this successful.”

Sherlock finally bristled at that. “Mycroft --”

“I’m _sorry_ , Sherlock, please, just relax. What I mean is, I’m _actually_ sorry.” Mycroft was gesturing Sherlock back into his chair. “Now that I see the woman that dear Sherrinford has become, I’m starting to think that you were probably the most short-changed of the three of us in the end. Please, Sherlock, give me one chance to make some part of this right again. Just play along for tonight.” He absolutely hated the way that his voice sounded right now, such a tediously ordinary and pleading tone, but if it was effective...

Sherrinford watched this exchange closely, and after an unpleasant look at her Sherlock subsided into his chair. Mycroft took a slow, deep breath, accompanied by a brisk inventory of his internal state and resources, and finally a razor-sharp assessment of the two human beings — his closest blood — seated in front of him, both of them vibrating lightly with anticipation. 

“Very well, little sister, dearest brother. I want the two of you nude, now. Quickly, please.” Mycroft took a series of slow, steadying sips from his tumbler as he watched them each disrobe with little self-consciousness, stripping their clothes off with a brisk efficiency that he could never have matched. With a mischievous glance at each other, they even each folded their garments neatly and left them in a stack on the chairs that they’d vacated, just as he’d had them do when they were young. Mycroft felt his own pulse pick up in angry, aroused anticipation as they turned to regard him expectantly, awaiting further direction. Sherlock in particular was covering his interest with a smirk.

 _The children first. You last._ Same as before. Same as always.

He picked up his tumbler and the bottle that he’d been pouring from and indicated with a jerk of his chin that they should follow him. He led them down a hallway with multiple open doors into bedrooms and a bath, but he went to the one closed door at the end without hesitation and opened it, leading the way in.

He heard both of their bare feet pad softly into the carpeted room behind him and then stall as they took it in. Mycroft turned -- he’d seen it before, and right now his eyes were only for them, their expressions, their reactions, their bare skins announcing every sign of their arousal to him. 

“Anthea swears to me that actual adults call it a dungeon with a straight face,” he told them conversationally. “As someone who regularly spends time in actual torture facilities, I find it difficult to do so. However, it is a better selection of equipment than we had access to at home, I must admit.”

Ostensibly ignoring them, though he was noting every wide-eyed reaction from the corner of his eye, Mycroft placed his bottle and tumbler on the table beside the wing-back chair that he’d placed right where he wanted it, by the fireplace, with a good view of the room. Sherlock was straining to seem nonchalant, but Mycroft saw his eyes traveling hungrily across the walls, hung with assorted ropes and cuffs and percussion instruments.

Sherrinford was drifting toward the sturdy, four-poster bed that was equipped with attachment points everywhere, including the crossbeams overhead. She glanced over at Sherlock frequently to note what in particular was catching his attention -- smart girl -- but then her own gaze would discover something of great interest to her own libido and she got distracted. But Mycroft was tracking both of their gazes, and waited patiently until he was sure that they had both put the next part together.

She looked at him first, then Sherlock did. 

“So we pick up exactly where we left off?” she asked in a sober voice, running a hand up one poster of the bed thoughtfully.

“We all know that there is a technical matter that we need to address before either of you will have clearer minds with which to make wiser decisions regarding the proceedings before us.”

He was watching her most closely -- she was the one who had been most traumatized by Mycroft’s failures as a young man, and what he was currently proposing certainly involved all of them jumping back into the deep end. But then, she had placed the reins back in his hands quite deliberately, and she must have known exactly where he would take it first.

Sherlock was looking at her too… this was really, primarily, about one of his own original kinks, albeit one that had driven Sherrinford around the bend with desire once Mycroft had gotten to work on her about it. Her eyes, mirrors to his, were fixed on him, hotly.

“Yes. There’s no point to playing around about it, is there?” With those words, she crawled onto the bed, situated herself right in the center of it, and knelt back on her heels, facing the foot of the bed.

Mycroft glanced over and saw that Sherlock was quite pale at the prospect before him. He started to move, uncertainly, but Mycroft held up a silent hand. Sherlock paused instantly.

“I will do the rigging this time," Mycroft said. "We need it to be perfect.”

He honestly expected a fight for implying that Sherlock might make a mistake, and was relieved when he didn’t get it. Sherlock and Sherrinford were still staring at each other, eyes locked. Fine, good distraction. Mycroft knew what he was doing.

He took his time with the rigging, never climbing onto the bed further than a single knee, unwilling to rumple his trousers, but Sherrinford offered him each of her bare limbs cooperatively, almost on autopilot. Sherlock stood at the foot, watching intently, opening and closing his fists, his erection firm in a way that he’d not yet been physiologically capable of the last time Mycroft had seen him in this light.

He soaked in the feeling of Sherrinford’s skin beneath his fingers, the first touch that he’d had from her other than that one single, terrified hug on her arrival at Christmas. He recorded every minute of it now, aware that his own heart was stuttering constantly at the shock of getting to touch her again.  He refused to let it show, focusing on tying and turning every knot to lay perfectly against her long, lean body. It was a complicated rigging, but both he and Sherlock had done it on enough occasions that he remembered every detail. He lifted her curls from the back of her neck and placed the loops of rope about her throat with deft hands, then the cross-ropes that held them away from her windpipe, and she shuddered deliciously at his hands and the ropes on her bare skin. 

She spoke, looking at Sherlock. “I’ve brought myself off thousands of times imagining this moment.”

He was biting his lip now, looking strangely like he had as a boy, watching as Mycroft carefully constructed the sliding knots at the critical points on the rigging, his eyes flickering back and forth between the ropes and Sherrinford’s face. One hand pressed against his erection almost absently, and Mycroft was pretty sure that he didn’t even know he was doing it.

“Imagining, or remembering?” Sherlock asked, in a hoarse voice.

“Both. Mostly just wishing that you’d actually done it that last time.”

Mycroft gave a slow but insistent pull on two of the ropes, and all of Sherrinford’s body suddenly shifted within her increasingly elaborate bonds. There were loops of rope at her wrists, elbows, ankles and knees now, long lead lines from each point that led to the ropes carefully arranged across her throat and torso. As Mycroft made the final adjustments, Sherrinford’s thighs were pulled a little wider apart, her elbows a little closer together behind her back, her back arched slightly.

Mycroft stood back and regarded his work. Sherrinford was panting lightly now, her nipples prominent between the ropes that crossed her breasts. Her labia were so swollen and slick that the parting of her thighs had caused them to part as well, just a few millimeters, enough to show her glistening pink inner folds.

He looked over at Sherlock, who was nearly transfixed by the sight of his bound sister. He climbed onto the foot of the bed slowly, situating himself  between her spread thighs. His swollen erection bobbed with great interest, but he ignored it for a moment, drinking in the sight of her in the ropes.

His voice was still low and rough. “This is definitely what you want?” he asked, and Mycroft could hear that it nearly killed him to ask -- what if she said no? -- but that even he needed this final reassurance, given how spectacularly their lives had been impacted by the single time that Mycroft hadn’t bothered to find out beforehand and had been wrong about it.

“Why don’t you _check?_ ” she asked pointedly, rocking her hips the little bit that she could, in invitation. Mycroft smiled in pained appreciation. They had sometimes made a point out of “checking” her, partly in order to touch her but also to prove to themselves that she was as interested in their games as they were, since as a girl she didn’t display the evidence as blatantly as they did. It was still a stupid point, given the frequency with which she’d been the one to initiate such games.

Sherlock gingerly slid a single digit into her folds, stroking upward once with an audible wet sound. “There, do I want it enough for you, dear brother?” she asked breathlessly, as if the answer weren’t obvious.

“Jesus,” was what he said, closing his eyes briefly as if in consternation, his erection throbbing noticeably. Mycroft was aware that Sherlock’s eyes were following the lines of the ropes obsessively. He obviously knew that Mycroft’s rigging was impeccable, but was clearly too excited by the implications to do otherwise. 

“This is how you always wanted to do it, Sherlock, except this time you’re actually, finally going to do it.” His voice was low, but it seemed to prod Sherlock, shake him out of his stunned reverie, and in response he moved forward over her, positioning himself, sliding the head of his erection against the hottest, slickest, most yielding part of her.

“Ah god, Sherlock, yes,” she panted immediately, trying to press up to sheath him, though of course she could accomplish no such thing. Sherlock braced himself on one trembling arm and paused there, his fist wrapped around his shaft in a death grip that almost made Mycroft wince in sympathy.

“Just like Dolores Cepeda. Just like Sonja Johnson.” Sherlock groaned as Mycroft spoke, the same words he’d used before to try to provoke Sherlock into forgetting himself and pushing forward. God, Mycroft had wanted them to do this, had spent nights calculating how to manipulate them into it, but had never been willing to make it a direct order. He’d even known there was a significant possibility they would have done it if he had simply forced the issue, but he’d wanted it to be like this. 

Now he stood by the bed, tumbler in hand, watching it unfold in utter fascination. “It’s these two ropes here, that really create the functional effect,” he explained, knowing full well that they both knew this full well, and while they normally three-for-three eschewed redundant speech, this was the Holmes equivalent of dirty talk. He traced the ropes in question with careful fingers. “Buono used a slipknot instead of a running bowline, which transferred too much of the kinetic energy into rope burns. Not this way, though. Between Sherlock’s modification and mine, this will work perfectly.”

They were one simple thrust away from no longer being a couple of unusually attractive late-30s virgins, but Mycroft relished the way they were drawing it out. Sherrinford was mewling but she was truly quite helpless, and Sherlock was shaking between her thighs.

 _Almost_ helpless. She could talk. “Fuck me, Sherlock. Come _on_ , I’m not twelve years old and you’re not thirteen and we both know what we’re doing even if we’ve never technically done it. I know what’s going to happen and I know how good it’s going to be for you. _Do it_.”

Mycroft closed his eyes to better appreciate the exquisite hotness of Sherrinford begging Sherlock to have sex with her like this. Sherlock’s breathing was broken, ragged, and he was sweating. Mycroft had to watch again, it was too delicious to see how torn Sherlock was about doing it even after all this time, even after Sherrinford had come all the way home just to ask for it.

She strained up toward him even harder, as if she could draw him into her by force of will or desire alone. “Come on, Sherlock,” she prodded in frustration. “Fuck me like you’re going to murder me, fuck me until I can’t breathe. There’s no other way I’d let you do it. I’ve always known it would be like this, haven’t you?”

Apparently they were the magic words. Mycroft felt his fingers tighten on his tumbler as Sherlock groaned loudly and finally pushed forward. It was not a smooth motion -- Christ, Sherrinford must be tight, and it was clearly an effort for him to breach her, his muscular backside and thighs tensing. She gasped loudly, her thighs twitching and tightening, her head thrashing from side to side as she struggled to adjust to the invasion. 

“Sherrinford,” he was saying her name, even as he seated himself fully, giving his hips a final jerk.

“Sherlock,” was her response, her body straining against the ropes, as she could literally do nothing else. “No, Christ, don’t stop, you prat, just fuck me. Fuck me to _death_ , please, now, _do_ it.”

And Sherlock pulled back, his eyes blazing as they locked on her, and he began to drive into her, _hard_.

Mycroft had been taking a sip of cognac when Sherlock finally gave in, and he found himself stalled with the glass at his lips as he was overwhelmed by the vigor with which his siblings went from virginal to… _this_. Sherlock braced himself on both arms above her and began to thrust, and with every thrust her thighs were pulled just a little further open, her arms into a slightly stricter position behind her back, and the ropes about her throat slipped just a little tighter.

Sherlock was clearly wild with desire, and yet his eyes were fixed on her hungrily, watching the ropes tighten and shift by tiny increments, her breathing becoming slowly more labored, her eyes wilder, her thrashing a little more panicked. Sherlock’s muscles were flexing, his thrusting smooth and deep now as he quickly got the hang of it.

The ropes around her throat were rigged to require a long series of deep thrusts in order to tighten enough to cut off her breathing, so right now she was still kilometers away from being in any danger, but both of the male Holmes were completely captivated by watching the incremental threat intensify. She was only panicking because it was so tight, which was a nearly automatic response, but really she was still getting enough oxygen, relatively speaking.

She couldn’t speak very clearly now, but she managed to cough out Sherlock’s name a few times. Mycroft was completely forgotten, which was as it should be, and did nothing to relieve the intensity of seeing his most cherished adolescent fantasy become a reality before his eyes. He refused to touch or stroke himself, restricting himself to watching, to recording without the distraction of his physical pleasure to obstruct any details. 

It was important that he remember everything about this for the rest of his life.

Sherrinford was going a little pink now, and it was difficult to tell if Sherlock was drawing to a close or not because he had started off with such ferocity. But then he somehow managed to build to an even greater crescendo, and Mycroft was keeping a close eye on Sherrinford’s vitals in order to ensure that things didn’t get out of hand. He reached over and discretely took her pulse, which was strong and steady, and then left his fingers there as Sherlock suddenly threw his head back with gritted teeth and made a loud, lengthy sound of release.

She was gasping, her color alarming now. Mycroft leaned in, careful to stay out of Sherlock’s way, and slid two fingers between Sherrinford’s pale throat and the ropes that obstructed her airway, in exactly the position that would let just a little bit of oxygen through to her brain. Her eyes rolled his way in desperate gratitude, and Mycroft raised an eyebrow at her.

Sherlock’s head was hanging down now, and he gave a couple of grunts and shudders in quick succession. He then showed a relatively clear-headed sense of brotherly concern as he came to himself in time to glance up and confirm that Mycroft had stepped in to avert Sherlock’s crisis once again. Sherlock just gave Mycroft an exhausted, amused smirk even as he finally let himself collapse over Sherrinford’s strained body.

She was lost enough to her own arousal -- unless Mycroft was very much mistaken, and he wasn’t, the rigging had driven Sherlock to his orgasm just a _little_ too quickly for her to achieve her own. Sherlock bothered to notice that his stupor was at the expense of her discomfort rather promptly, and he rolled himself out of the way and sat up, running his fingers through his sweat-damp curls and collecting himself, assuming that Mycroft would handle the clean up.

Mycroft found himself with Sherrinford all to himself and quite at his mercy for a moment, though he hadn’t exactly meant to put her in a so sinister a position with regards to himself. He looked down at her closely, breathing just enough now that she wasn’t struggling for release, but they both knew that she would have about two minutes to live if Mycroft removed his fingers from where they were.

She was out of her mind with arousal. Oh, she didn’t want him to stop, and indeed Mycroft might have feared for his continued authority had he carelessly denied her this. She was still as good as they both had always been at eroticizing anything that would send sane humans like John Watson and Anthea screaming in self-preservation.

Mycroft supposed he had no room to talk.

He reached over and placed the tumbler on the bed, as there was no better surface that he could reach without putting her life in peril. Her eyes watched him do this, and he knew that she was aware that he was freeing up a hand in order to --

She sighed in relief as he reached down and tugged on her turgid nipple. She rocked her hips the little bit that she could now that the ropes had pulled her into such a severe position, and Mycroft knew that she was aching, aching to orgasm.

Sherlock had pulled himself together now, and reappeared between her thighs, this time with an act in mind with which he had some prior experience. Sherrinford moaned as loudly as she could with the limited air she was getting, pressing herself down onto his warm, questing mouth. Mycroft marveled at the sight of the famously-indifferent-to-sex Sherlock Holmes enthusiastically performing oral sex on a woman.

Sherlock’s eyes were locked on Mycroft’s fingers keeping Sherrinford alive as he buried his face between her trembling thighs and quickly urged her through her own sexual response cycle. Mycroft could deduce from the flexion of Sherlock’s bare shoulder that he was touching himself even though he had orgasmed about two minutes ago. But that was Sherlock, usually so ascetic and then on occasion an utter glutton, the chronic insomniac who often slept for two or three days straight twice a month, the anorexic who gorged himself at the end of every good, multi-day case. The asexual who could be  induced into a near-manic sexual state with _just_ the right stimulus.

If that stimulus happened to be Sherrinford and Mycroft.

Sherrinford orgasmed quietly, only because she had no voice, but that was not to say that she orgasmed unviolently. She thrashed and strained in her bonds, and Sherlock wrapped his strong forearms around her shaking thighs and held her tight, his mouth just as pushy in this way as it was in every other. He continued to suck lightly on her clitoris straight through her orgasm and past the point when the stimulus was clearly over the too-much line for her.

“Sherlock,” Mycroft said warningly. He’d learned his lesson about pushing too far, and everything that happened between them now was going to be on the up-and-up... well, as up-and-up as secret sibling incest could be, he supposed. Sherlock sat back and grinned, apparently unbothered by her fluids on his mouth and chin, and they both watched Sherrinford slowly subside in her bonds, shaking with a series of aftershocks from her incredible climax.

Mycroft raised his eyebrows. “That appears to have worked out quite well for both of you,” he remarked drily.

Sherlock was still enviably un-self-conscious, even in the aftermath of orgasm and covered in their combined biological filth. He absently wiped his chin, then reached forward and deftly untied each of the two knots that would relieve some of the pressure around her throat. 

Mycroft had mixed feelings about the painful return of sensation to the fingers that had been trapped under the ropes against her windpipe, keeping her alive through Sherlock’s orgasm and her own. That hadn’t exactly been part of any of the narratives with which Mycroft had incited each of them to enact this scenario when they’d been younger, but he had to admit that it was a mind-bogglingly arousing capstone to one of the most persistent sexual fantasies of his admittedly limited sexual repertoire.

Mycroft was sure that his own raging, untended erection was going to kill him if he didn’t get himself under control soon, and he forced himself to retire to his chair and pour himself a new glass of cognac with a hand that shook with desire. He needed to give them some time to recover, and to gauge both of their moods now that they’d passed through the first pivotal moment and its accompanying release. One or the other of them had occasionally crashed after coming down off the first high, which was exactly what had gotten a young, uncareful Mycroft into so much trouble.

But no, they were curled up together contentedly enough on the bed, and Sherlock was admiring the deep ligature marks on Sherrinford’s wrists, ankles, and thighs, almost all of which were certainly going to bruise. She simply lay back and dozed and let him move her about to examine her. 

It was Sherlock that he had some concerns about, but with some deft handling on his own part and on Sherrinford’s, he seemed unrebellious at the demands that the evening’s activities were putting on him. And outwardly enthused at the opportunities for experimentation that having access to Sherrinford’s body was going to open up, and he even had Mycroft to make sure that he didn’t do anything too likely to be lethal. Mycroft had to admit to a small measure of internal relief at Sherlock’s assumption that Mycroft would obviously be present for any future experimentation.

Christ, what were they getting themselves into? Mycroft feared that it wasn’t just a weekend.

On the other hand, he feared that it was.


End file.
